<template>
  <div>
    <h3>树形控件</h3>
    <el-input placeholder="输入关键字进行过滤" v-model="filterText">
    </el-input>
    <!-- show-checkbox 显示复选框-->
    <el-tree :data="treeData" :props="defaultProps" @node-click="handleNodeClick" show-checkbox>
    </el-tree>

    <el-tree :props="defaultProps" show-checkbox lazy show-checkbox :load="loadNodes" :filter-node-method="filterNode">
    </el-tree>
    <div class="buttons">
      <el-button @click="getCheckedNodes">通过 node 获取</el-button>
      <el-button @click="getCheckedKeys">通过 key 获取</el-button>
      <el-button @click="setCheckedNodes">通过 node 设置</el-button>
      <el-button @click="setCheckedKeys">通过 key 设置</el-button>
      <el-button @click="resetChecked">清空</el-button>
    </div>
  </div>
</template>

<script>
  export default {
    watch: {
      filterText(val) {
        this.$refs.tree.filter(val);
      }
    },
    data() {
      return {
        filterText: '',
        treeData: [{
          id: 1,
          label: '一级 1',
          children: [{
            id: 4,
            label: '二级 1-1',
            children: [{
              id: 9,
              label: '三级 1-1-1'
            }, {
              id: 10,
              label: '三级 1-1-2'
            }]
          }]
        }, {
          id: 2,
          label: '一级 2',
          children: [{
            id: 5,
            label: '二级 2-1'
          }, {
            id: 6,
            label: '二级 2-2'
          }]
        }, {
          id: 3,
          label: '一级 3',
          children: [{
            id: 7,
            label: '二级 3-1'
          }, {
            id: 8,
            label: '二级 3-2'
          }]
        }],

        defaultProps: {
          children: 'children',
          label: 'label',
          isLeaf: 'leaf'
        }

      }

    },
    components: {

    },
    methods: {
      filterNode(value, data) {
        if (!value) return true;
        return data.label.indexOf(value) !== -1;
      },
      getCheckedNodes() {
        console.log(this.$refs.tree.getCheckedNodes());
      },
      getCheckedKeys() {
        console.log(this.$refs.tree.getCheckedKeys());
      },
      setCheckedNodes() {
        this.$refs.tree.setCheckedNodes([{
          id: 5,
          label: '二级 2-1'
        }, {
          id: 9,
          label: '三级 1-1-1'
        }]);
      },
      //通过key设置
      setCheckedKeys() {
        this.$refs.tree.setCheckedKeys([3]);
      },
      //清空
      resetChecked() {
        this.$refs.tree.setCheckedKeys([]);
      },
      handleNodeClick(data) {
        console.log(data);
      },
      loadNodes(node, resolve) {
        console.log(node, resolve);
        if (node.level === 0) {
          return resolve([{
            label: '浙江'
          }]);
        }
        if (node.level == 1) {
          return resolve([{
            label: '嘉兴'
          }]);
        }
        //leaf 是否是子节点，是否有更多箭头
        setTimeout(() => {
          const data = [{
            label: '南湖区',
            leaf: true
          }, {
            label: '秀洲区',
            leaf: true
          }];
          resolve(data);
        }, 500);
      }
    }
  }
</script>

<style>
</style>
